The Torrent Key is a key item that appears in Wario: Master of Disguise.
The Torrent Key is a small green key with, as Wario states, a round design on the end.
The Torrent Key can be found in Ancient Waterworks and is one of four keys that can be used in the level. The Torrent Key can be used on the door with the round design on it. It can be found at the top floor of the ruins behind a fake wall where Genius Wario is required to get to it.